Easyjet's rule seems strict and clear: its website and tickets insist "all passengers provide photographic ID at check-in on all flights, including domestic services". So when Arnie Wilson, a magazine editor from Haywards Heath, turned up at Gatwick this month for a flight to Edinburgh only to realise he had neither his passport nor his driving licence, he started to panic.

Check-in staff confirmed the requirements for photo ID but, as Wilson began to make plans to have his passport couriered from home, they offered a helpful alternative - he could make his own.

"They suggested I go to the railway station within the terminal, buy a season ticket and with it get a photocard, which they'd then accept as ID," Wilson said. "In fact, it was even easier and didn't cost a penny. Southern Rail gave me a photocard and sent me upstairs to the public photo booth. I asked if I needed to come back to the ticket office with the photos; they said, no, I should just fill in the card myself then seal down the plastic covering."

Easyjet accepted the DIY identity without question. Wilson added: "Of course I was glad to get the flight but I couldn't believe it - what's the point of Easyjet asking for photo ID if you can get it done like this, and their staff even tell you how to do it? Obviously it was only a domestic flight, but then so were all the planes hijacked on 9/11."

A spokesman for the airline said the requirement for photo ID was introduced to enhance security after the attacks on New York but that rail photocards are acceptable on domestic flights (even though they are not listed as such on the airline's website). "Check-in staff also have extensive training in assessing whether a passenger is a security risk," the spokesman said.

The case highlights the bizarre situation regarding domestic flights in the UK. In 2006 the government passed controversial legislation giving police access to passenger-name records on domestic flights. The move, part of the Police and Justice Act, prompted the then Liberal Democrat home affairs spokesman, Alistair Carmichael, to complain that "the government is building a surveillance infrastructure unparalleled in the free world". Unparalleled, perhaps, but also deeply flawed.

Unlike in the United States, there remains no legal requirement for airlines to ask for photo ID on domestic flights, so the carriers have decided their own policies, which vary significantly. Ryanair demands passport or driving licence, Easyjet accept railcards, and British Airways asks for no photo ID at all. Without photo ID, anyone can fly using a made-up name, at a stroke rendering all security "watch lists" of suspected terrorists - as well as the new legislation - useless.

The Home Office denied there was a problem, arguing that even if suspected terrorists did board domestic flights, airport scanners meant they would be unable to carry on weapons so they "would only have their bare hands".